Hierarchical growth of vertically standing Fe3O4-FeSe/CoSe2 nano-array for high effective oxygen evolution reaction

Abstract Large-scale electrochemical water splitting is hindered by the sluggish oxygen evolution reaction (OER) kinetics. In this work, we report a vertically standing Fe3O4-FeSe/CoSe2 hierarchical structure material grown on carbon cloth as a highly active OER electrocatalyst. Benefiting from the rock-like Fe3O4 particles on the carbon cloth, the CoSe2 nano-arrays are more firmly affixed onto the carbon cloth. In addition, small amount of FeSe particles adsorbed on the CoSe2 arrays offer a synergistic advantage, in which CoSe2 achieved a small 279 mV overpotential at a current density of 10 mA cm−2 and a low Tafel slope of 68.78 mV dec−1. By comparing the performance of Fe3O4-FeSe/CoSe2 with pure CoSe2 and Fe3O4-FeSe, it demonstrates to be the most efficient OER catalyst. Significantly, the hierarchical structural strategy of fixed Fe3O4 growth on carbon cloth arrays introduces a new concept to explore the design of high efficiency OER electrocatalysts.